Hi,
The house right next to us is being built with ICFs -- so, I've watched one being built
There is some info here:
http://www.builditsolar.com/Projects...tionps.htm#ICF
I think its not a bad way to go. The blocks they were using on the house next door were 2 inches of foam on each side of the concrete -- so, about R20 with little thermal bridging -- pretty good. The thermal mass makes it behave like a wall with a little higher R value -- about 40% better for cold climates.
See the ORNL paper at the link above.
There are some types of these that have the thermal mass (concrete) on the inside with insulation all on the outside -- these will perform better thermally.
The ORNL paper covers this as well.
The R value claims that some of the people who sell these things are completely bogus, so be careful on that score.
The process of putting the blocks up and getting them filled took a lot longer than I expected. It may be that the crew was inexperienced.
I've heard (and Texican would seem to confirm) that they are not cheap. But, they are definitely getting more popular around here.
If you look around on the same page that link goes to, there are getting to be lots of energy efficient wall system options around.
Gary
